This proposal is for the purchase of a SkyScan 1176 In-vivo Micro CT system, which will add new capabilities to our core of users. The seventeen laboratories collaborating in this venture are involved in a wide range of NIH-funded ventures, and we have a history of working together successfully in this shared facility. To facilitate administration of this shared equipment we have partnered with the Indiana Institute for Biomedical Imaging Sciences, who provide campus-wide assistance with biomedical imaging. The request for a Skyscan 1176 system has a three-fold rationale: adding in vivo scanning capability, allowing large specimen ex vivo scanning, and reducing capacity on the present CT system. The present micro CT system (a SkyScan 1172, obtained in 2007) provides excellent imaging of mineralized tissues, but can be used only for ex vivo specimens. The SkyScan 1176 will enable researchers to utilize experimental protocols that can monitor the changes in tissue over time in their experimental animals, thereby provided longitudinal data while simultaneously using fewer animals. The SkyScan 1176 will also allow the scanning of larger intact specimens (like pig hearts and human kidneys) which cannot be accommodated on the present system. With regard to capacity, the present system cannot handle the high volume of micro CT imaging demanded by NIH-funded projects on this campus. The SkyScan 1176 can be used to scan many of the specimens now being scanned on the old 1172 system, with identical parameters, and so relieve pressure on the present facility. The SkyScan 1176 system is complementary to the presently existing system. This means that minimal retraining will be required for present users. Moreover, for most users the two systems can be used interchangeably, so that the present full load on the existing system can be relieved, thus allowing every laboratory to obtain data on its specimens in a timely manner.